Hierarchical-structure-dependent high ductility of electrospun polyoxymethylene nanofibers

Two types of electrospun polyoxymethylene nanofibers with rough and smooth surface morphologies [rough fibers (RFs) and smooth fibers (SFs), respectively] were successfully prepared via the control of the electrospinning voltages. Mechanical tensile tests showed that the RF nonwoven mats exhibited a much higher elongation (440%) than the SFs (180%) without sacrifices in the stiffness and strength. Scanning electron microscopy characterization revealed that the large ductility of a single RF resulted from its unique multiple-necking mode, which was induced by its rippled structural features. In the meantime, the large ductility led to a high molecular orientation under tension and further improved the strength and toughness of the RF nonwoven mats. In comparison, the SF behaved in a single-necking deformation mode, and this led to a rapid rupture behavior. This surface-morphology-dependent mechanical behavior helped us to deeply understand the relationship between the structure and properties and should guide the development of high-performance materials for load-bearing applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47086.     

短桩与锚杆组合应用的复合型杆塔基础数值模拟分析

短桩与锚杆组合应用的复合型杆塔基础是一种应用于上覆浅土层岩石地基的新型杆塔基础。以某500 kV输电线路工程为背景,开展了新型基础设计,并应用FLAC3D有限元程序对该型基础的6种模型进行数值模拟。结果表明：短柱与锚杆组合应用的复合型基础可以满足输电线路杆塔基础荷载的要求,短柱底部施加锚杆可以显著提高基础的抗拔承载性能,但对抗倾覆性能的提高较小,此时可以通过增大立柱直径与增加基础埋深来提高高露头复合型基础的抗倾覆能力。     

引入节能技术的有轨锻造操作机液压系统改造

简要介绍有轨锻造操作机的功能,针对它在使用中出现的问题,分析其原因。提出具有节能特点的优化液压系统改造方案。改造后的液压系统在实际使用中达到了很好的效果,为相关类产品设计提供了参考。     

层次分析法在煤矿瓦斯治理安全投资中的应用

为了充分合理利用煤矿瓦斯治理安全投资资金,选择合理的安全投资方案,基于国家瓦斯治理的工作方针和体系要求,根据某煤矿的实际情况,采用层次分析方法(AHP)对该矿瓦斯综合治理安全投资指标进行了分析,确定了各指标的权重,并将量化的结果作为确定煤矿瓦斯治理安全资金的优先投入顺序的依据。结果表明:瓦斯系统和装备、矿井通风是投资决策的主要影响因素,计算分析结果符合实际情况,为煤矿瓦斯治理安全投资指明了方向。     

微生物酶活性对猪粪堆肥含氮量的影响

目的:脲酶和过氧化氢酶在提高猪粪堆肥含氮量中起关键作用。方法:通过18天30℃恒温堆肥实验,测定猪粪中脲酶、蛋白酶、过氧化氢酶、亚硝酸还原酶、硝酸还原酶的活性。结果:脲酶活性和过氧化氢酶活性显著相关(P0.01),过氧化氢酶活性和硝酸还原酶活性显著相关(P0.01),脲酶活性在第九天开始迅速下降。结论:建议堆肥的第9天为投加脲酶抑制剂的最佳时机。     

大气压氦气多脉冲辉光放电径向光学演化过程

介质阻挡放电(dielectric barrier discharge,DBD)的径向演化及其影响因素对研究低温等离子体的机制具有重要的参考价值。采用铟锡氧化物(indium tin oxide,ITO)透明电极,进行了大气压氦气介质阻挡三脉冲辉光放电试验,利用增强型电子耦合器件(intensified charge-coupled device,ICCD)拍摄放电的侧面短时曝光照片来诊断放电模式,拍摄放电的底面短时曝光照片并绘制其发光灰度值在电极表面的三维分布图来研究放电的径向演化过程。结果表明:放电首先在圆形电极的边缘区域发生,逐渐向电极中心发展,最后又转向电极边缘并逐渐减弱;随着电流脉冲次序的增加,放电在电极中心发展越来越充分;电极结构的限流作用同外施电压和介质表面电荷一样,对径向位置上不同时刻的放电演化过程起着重要作用。     

含非规则粗糙间隙表面铰链关节的平面柔性多连杆传动系统动态误差与运动副磨损周期行为分析

传统旋转间隙关节接触模型假定销轴和衬套接触面形状是规则的并忽略了磨损效应的影响,降低了机构动力学模型预测精度。提出了一种含非规则粗糙间隙表面铰链关节的平面柔性多连杆机构多体动力学建模、磨损预测和动态误差分析方法。为准确描述运动副元素间碰撞行为,考虑滑动轴承间隙关节的磨损效应,提出了一种非规则粗糙间隙表面铰链关节的改进接触模型。在此基础上,考虑柔性杆的影响,基于绝对节点坐标法建立了含非规则粗糙间隙表面铰链关节的平面柔性多连杆传动系统多体动力学模型。与基于传统光滑间隙模型的结果相比,基于非规则粗糙间隙改进模型的多连杆机构动态响应更接近于试验值,验证了所提出计算方法的有效性。仿真结果表明,选用CuSn10P和CuPb30作为铰链衬套材料能够有效降低多连杆机构滑块动态响应偏差和提高机构的运动精度;表面粗糙度过高会导致运动副磨损加剧,过低则会降低间隙表面微凸体对碰撞能量的吸收。此外,磨损加剧了间隙表面轮廓不规则度,导致机构动态响应的不稳定性增大,运动精度降低。     

Systematic investigation on anode etching residue widely generated in manufacturing of low-temperature polycrystalline-Si active matrix organic light-emitting diode

Etching residue is a kind of thorny technological issue in the manufacturing of flat panel. In this work, we report on a systematic investigation on anode etching residue which is widely generated in the manufacturing of low temperature polycrystalline Si-active matrix organic light emitting diode (LTPS-AMOLED). Firstly, we proposed three kinds of residue formation mechanisms, including the Bernoulli equation-based dynamic process, as well as two other situations caused by absence of electrochemical accelerated reaction and organic residue in preprocessing, respectively. Then, residue related failure model of product defects was clarified and considered to give rise to ~3.1% product yield loss owing to the related phenomenon named dark line. Finally, we provided three solutions based on the formation mechanism and failure model, and superior process and design implementation conditions were obtained with detailed experimental verifications, which can be promising methods to solve other related issues in the manufacturing to bring cost down.     

真空激光准直系统 在大坝安全监测中的应用及发展

本文对真空激光准直系统在大坝监测中的应用情况和使用效果加以评价 ,并介绍真空激光准直系统近期的发展情况     

对东北水电站更新改造的看法

东北水电站设备改造虽已取得了很大的成绩，但还应该借鉴瑞士等国先进的经验，即最大限度地利用水能，解决可靠性，改造要为提高机组效率、出力，降低成本和增加发电量，更新不能仅追求先进技术，而应以增加经济效益为目的。